The present invention covers a series of fluorenamine, dibenzofuranamine and dibenzothiophenamines, derivatives useful in the treatment of cerebrovascular disorders.
U.S. Pat. Nos. 3,159,677, 3,206,480 and 3,111,527 are concerned with fluorenamines, dibenzofuranamines, dibenzothiophenamines and processes for preparing them. The compounds have useful central nervous system depressant activity.
Excessive excitation by neurotransmitters can cause the degeneration and death of neurons. It is believed that this excitotoxic action is mediated by the excitatory amino acids, glutamate and aspartate, acting at the N-methyl-D-aspartate (NMDA) receptor. This action is responsible for neuronal loss in cerebrovascular disorders such as: cerebral ischemia or cerebral infarction resulting from a range of conditions such as thromboembolic or hemorrhagic stroke, cerebral vasospasm, hypoglyceMia, cardiac arrest, status epilepticus, perinatal asphyxia, anoxia such as from drowning, pulmonary surgery and cerebral trauma. Thus the compounds of the instant invention which are active as noncompetitive antagonist of NMDA receptor mediated ion channel activation are useful in the treatment of the above disorders. In addition, by this NMDA antagonist action, the compounds of the instant invention are also useful for treating schizophrenia, epilepsy, spasticity, neurodegenerative disorders such as Alzheimer's disease, or Huntington's disease, Olivo-pontocerebellar atrophy, spinal cord injury, and poisoning by exogenous NMDA poisons (e.g. some forms of lathyrism). Further uses are as analgesics J. Pharmacol. Exp. Ther., 243, 9, (1987) and anesthetics, particularly for use in surgical procedures where a finite risk of cerebrovascular damage exists.
There are no specific therapies for these neurodegenerative disorders, but competitive and non-competitive NMDA antagonists acting specifically to antagonize excitatory neurotransmission at NMDA receptors offer a novel therapeutic approach to these disorders; B. Meldrum in "Neurotoxins and Their Pharmacological Implications" edited by P. Jenner, Raven Press, New York, 1987. Recent literature reports have confirmed the protective action of examples of this class of agents in pharmacological models of neurodegenerative disorders (J. W. Mcdonald, F. S. Silverstein and M. V. Johnston, Eur. J. Pharmacol., 140, 359, (1987); R. Gill, A. C. Foster and G. N. Woodruff, J. Neurosci., 7, 3343, (1987); S. M. Rothman, J. H. Thurston, R. E. Hauhart, G. D. Clark and J. S. Soloman, Neurosci., 21, 673, (1987); M. P. Goldberg, P-C. Pham and D. W. Choi, Neurosci. Lett., 80, 11, (1987).
The present invention provides a method of prevention and/or treatment of the aforementioned pathological conditions by the administration of specific, orally active non-competitive NMDA receptor antagonists.